Less than a week ago a Sunday paper published the results of an opinion poll into the public's attitudes to Kate and Gerry McCann. For a couple who had enjoyed unprecedented global support following the apparent abduction of their daughter Madeleine in May, its findings were chilling. Only 20% of respondents said they thought they were completely innocent and 48% said they believed the McCanns could have been involved in their daughter's death.

The poll followed 10 terrible days for the couple in which they had been named as suspects in Madeleine's disappearance and confronted by evidence allegedly "proving", among other things, that traces of their daughter's DNA had been found in the rear of their hire car.

They were, says a friend, "going through absolute torture", the most remarkable publicity campaign of recent times having spiralled out of control.

Six days after the Sunday Times poll the McCanns remain suspects in the investigation, and their daughter is still missing. But the past week has seen a striking turnaround in their campaign. On Wednesday it was announced that they would not, for the time being, face further questioning, after the Portuguese attorney general ruled that local police had not gathered enough evidence.

Earlier, Clarence Mitchell, a former BBC reporter who assisted the couple on behalf of the Foreign Office in May and June, announced he had given up his job to work as their spokesman, believing them "innocent victims of a heinous crime".

Most significantly perhaps, the couple have amassed a world-class team of British and Portuguese lawyers, bolstered this week by the president of the Portuguese bar. As a front page headline in the Daily Mirror put it earlier this week: The Tide Turns.

The McCanns' legal position and public profile has been worsening for some months. For a long time, according to Gerry McCann's brother, John, they refused to accept that they should hire a lawyer. "Was it naivety or just total belief in their own innocence that they didn't think they needed a lawyer?" John McCann said yesterday. "They were so convinced that because of their close collaboration with the police they didn't need one."

The first small sign of a fightback, at his urging, was the appointment just over a month ago of Carlos Pinto de Abreu, a leading local human rights specialist, and their decision shortly afterwards to issue proceedings against a magazine that claimed police thought they had killed Madeleine.

But the hostile reports, apparently based on police leaks, became overwhelming. This week a senior Portuguese reporter, who has covered the case from the beginning, gave the first insights into the systematic way in which investigators passed on information to local journalists.

"A detective, not connected to the investigation, was appointed, who was told what he was allowed to say," the journalist told the Guardian. "He gave three or four off the record briefings in which he described details of the investigation [to a group of reporters]." The intention, he said, was to pass a message to the "British addicts" (the media), which had been critical of the investigation. "Here it is not done like that normally - police do not brief journalists."

Such briefings, added Carlos Anjos, chairman of the Union of Portuguese Detectives, were acts of self defence. "There was a temptation by detectives to use the Portuguese press as a means of counter-attacking," he said.

Another senior journalist said he did not think the McCanns were guilty, whatever the apparent weight of his paper's coverage. "There is one thing that is your personal conviction, and another that is your professional responsibility," Eduardo Damaso, deputy editor of the local Correio da Manha, said. "I find it very difficult to believe that the parents are involved, but as a journalist you have to present the information that you have."

Mr and Mrs McCann, say friends, were desperate for advice. They were in frequent contact with a number of high profile media figures in this country; Mr Mitchell, too, was regularly contacted for guidance. "Gerry rang him all the time," says one well-placed source, "he was calling him at 4am when he was upset, asking what he should do."

By the time they were named as suspects on September 7 several advisers had been urging them to return to the UK for the sake of their legal defence and their worsening reputation.

It would prove to be critical. On the day after they returned their new legal team was named. A week later Sir Richard Branson said he "trusted implicitly" in their innocence and was contributing £100,000 towards their legal defence, as were a number of other wealthy individuals - on condition of anonymity.

To date there are "a number of [sizeable] offers on the table", says a source, though Esther McVey, one of the Find Madeleine fund directors, said ordinary people were also contributing. Donations remained steady even while the couple were being criticised heavily, she said, though they are now split roughly evenly between the original fund and the legal defence.

Mr Mitchell is not paid by the original fund but by an anonymous benefactor, who will reportedly take him on as an employee once, as they hope, the couple are cleared of suspicion. A source close to the campaign said even he did not know who the benefactor was, but he had been told it was "not someone with a profile".

What is clear is that Mr Mitchell's appointment has coincided with a sense of impetus, as the couple have, for the first time, gone on the offensive against their critics. Friends have emerged this week to elaborate on some of the "entirely innocent" explanations they offer for the allegations against them. The apparent fightback led one newspaper to call Mr Mitchell "the English armada".

Mr and Mrs McCann are far from in the clear: DNA test results expected from the UK, for instance, may provoke further questioning, and more allegations may yet emerge. But for the moment at least, it seems the initiative is once again theirs.